288 
POPULAE SCIENCE EEYIEW. 
(Pagurus) may be luxurious enough to appreciate the soft cushion which 
Adamsia makes for his back and chest, or he may find that the white 
worm-like tentacles of Adamsia act as a sort of bait to small creatures, 
who thus bring themselves incautiously within the reach of Pagurus’ 
sharp claws.”— Annals of Natural History for November. 
Beetles new to Science. — Of Coleoptera, with long antennae, found in the 
Amazons, Mr. Bates establishes two genera : Lepturges, of which he 
describes twenty-three new species ; and Paraecus, whose species are not 
yet all described. 
The Skeleton of the Sirenia. — From a comparative examination of the 
skeletons of these animals, and those of Pachydermata and Cetacea, 
Professor Brandt concludes that the Sirenia are not to be regarded as 
Cetacea, but rather as Pachydermata whose habitat is a purely aquatic one. 
The Halitheria, which are now fossil, may be considered, from the fact 
that they present traces of hind limbs, as the highest forms of Sirenia ; 
whilst the Rhy tinee, from the absence of teeth in the adult, must be looked 
on as the lowest. Hence the Dugongs, from the possession of intermediate 
characters, form a connecting link between the Halitherige and Rhytinae ; 
the Manatees being collateral types related to such existing pachyderms 
as the tapirs. — Memoir read before the French Academy , September 
7th, 1863. 
Gases in the Swim-bladder of Fish . — In concluding his memoir on this 
question, M. Moreau observes : — The air in the swim-bladder of fishes 
presents a composition which in regard to the quantity of oxygen maj^ vary 
under the following conditions : — (1) The oxygen is diminished or entirely 
disappears during asphyxia and other morbid states. (2) In the fish 
whose swim-bladder is open, as in that in which the organ is closed, the 
air is renewed without being borrowed from the atmosphere, and the 
rapidity of this renewal is in proportion to the activity of the fish. 
(3) The air newly formed presents a far greater proportion of oxygen than 
the ordinary air of the swimming fish, and a greater proportion of oxygen 
than is dissolved in the surrounding water. The experiments were 
performed in Paris on the fresh-water fish, and the others in Bretagne, 
Concarneau, in M. Coste’s aquaria, which were placed at M. Moreau’s 
disposal. — Comptes Rendus , November 16th, 1863. 
The Classification of Gastropodous Mollusks receives the consideration of 
M. Gouriet who is dissatisfied with all existing schemes. In his opinion 
it is unjust to base any system of arrangement upon characters of the 
generative organs, as by doing so animals otherwise closely related are 
entirely separated. He seems to think characters of the respiratory apparatus 
afford a better clue to the true affinities of these beings. Nevertheless he 
objects to such expressions, now in use, as tubulibranch y which seems to 
imply that the gills are tubular and to those of cyclobranch and 
infer obranch , which he considers confusing. He says, the gills can only 
occupy three positions. Either (1) they are external ; or (2) enclosed in a 
special cavity, and generally covered by a shell ; or (3) they are simply 
protected by an incomplete covering. He suggests the adoption of the 
following terms to designate the three natural groups : — Exobranchia, 
Stegibrancliia, and Endobranchia. The animals included under the first 
